4-thiouracil compounds as fog inhibitors

ABSTRACT

4-Thiouracil compounds, including novel 4-thiouracil compounds, are prepared by reacting ammonia or primary amine with novel adducts of an alkoxycarbonyl isothiocyanate and a tertiary enamine. The 4-thiouracil compounds are useful photographic fog inhibitors.

United States Patent Robert W. Lamon Rochster, N.Y.

Aug. 12, 1968 Nov. 23, 1971 Eastman Kodak Company Rochester, N.Y.

lnventor Appl. No. Filed Patented Assignee 4-T1'I1OURAC1L COMPOUNDS ASFOG INHIBITORS 18 Claims, No Drawings US. Cl 96/109, 260/251 Int. ClG03c 1/34, C07d 5/18 Field of Search 96/109;

[56] References Cited UNITED STATES PATENTS 2,231,127 2/1941 Kendall96/109 FOREIGN PATENTS 484,595 5/1938 Great Britain 96/109 PrimaryExaminer-Norman G. Torchin Assistant Examiner-Richard E. FichterAttorneys-W. H. J. Kline and William E. Neely The present inventionrelates to a process for preparing 4- thiouracil compounds, to certainadducts of tertiary enamines and alkoxycarbonyl isothiocyanates usefulin the preparation of said 4-thiouracil compounds, to silver halidephotographic emulsions containing at least one of said 4-thiouracilcompounds, to photographic elements including fog-inhibiting amounts ofsaid 4-thiouracil compounds and to certain of said 2l-thiouracidcompounds as new compounds. More particularly, the invention relates toa process of preparing 4-thiouracil compounds by reacting adducts oftertiary enamines and alkoxy-carbonyl isothiocyanates with ammonia or aprimary organic amine, to novel adducts of tertiary enamines andalkoxycarbonyl isocyanates useful in the process, to silver halidephotographic emulsions containing at least one of said 4- thiouracilcompounds as a fog inhibitor, to light-sensitive photographic elementscontaining a support having coated thereon a silver halide emulsionlayer containing at least one of said 4-thiouracil compounds as anantifoggant and to certain of said 4-thiouracil compounds as newcompounds.

During development of a silver halide emulsion, small amounts of silverhalide are reduced to metallic silver regardless of whether or not theyhave been exposed. This eduction of silver ion produces a background fogwhich is more specifically referred to as chemical fog.

Chemical fog, apparent in most silver halide systems, has been reducedby prior art methods of processing exposed silver halide material in thepresence of compounds which restrict development of unexposed silverhalide. Such compounds can be incorporated in the silver halide emulsionor in the processing solutions for developing such silver halideemulsions. Compounds which have been found to have a chemicalfog-inhibiting effect on emulsions which have been subjected to hightemperature and high humidity conditions are referred to as emulsionstabilizers. On the other hand, compounds which have been found to havechemical fog inhibiting effects on emulsions which have not been exposedto adverse storage conditions are referred to as antifoggants. Althougha large number of emulsion stabilizers and antifoggants have been usedin the prior art, many of these compounds cause undesirable losses inemulsion speed and contrast and others lack adequate compatibility withemulsion gelatin. The 4-thiouracil compounds of the present inventionvery effectively prevent fog, particularly after storage of the silverhalide emulsions, without adversely effecting the speed or gamma.

It is an object of the invention to provide adducts of tertiary enaminesand alkoxycarbonyl isothiocyanates. It is a further object of theinvention to provide a process for preparing 4- thiouracil compounds byreacting said adducts with ammonia or a primary amine. Further objectsof the invention are to provide new 4thiouracil compounds, to providesilver halide photographic emulsions containing a 4-thiouracil compoundto reduce fog and to provide the light-sensitive photographic elementsreferred to hereinbefore.

The manner in which the foregoing objects and other objects of theinvention are accomplished in accordance with our invention will beapparent from the following detailed description of the invention.

The tertiary enamine utilized to form the novel adducts of the inventionhas the formula:

wherein R and R each represents an alkyl group such as methyl, ethyl,propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, octyl, decyl, etc.,for example, especially a lower alkyl group having 1 to 6 carbon atomsand a benzene nucleus, and wherein collectively represents a saturated 5or 6 membered heterocyclic nucleus such as l-pyrrolidinyl, piperidino,morpholino. l-pyrazolidinyl and 3-oxazolidinyl, for example, Rrepresents hydrogen, lower alkyl, lower alkoxy, carb(lower alkoxy) and abenzene nucleus, R represents hydrogen and lower alkyl, and wherein Rand R, collectively represent a polymethylene chain having at least twocarbon atoms, such as ethylene CH CH trimethylene -CH CH CHtetramethylene (CH Cl-l- CH CH pentamethylene (CH CH CH CH Cl-l andhexamethylene (Cl-l Cl-l-,CH Ch.,Cl-l Cl-l for example, and thustogether with the carbon atoms to which they are attached represent acyclobutenylene nucleus, at cyclopentenylene nucleus, a cyclohexenylenenucleus, a cycloheptenylene nucleus and a cyclooctenylene nucleus, forexample.

The term lower alkyl" when used herein and in the claims, unlessspecifically indicated otherwise, refers to an alkyl group having 1 to 6carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl,pentyl and hexyl, for example.

The term lower alkoxy when used herein and in the claims, unlessspecifically indicated otherwise, refers to an alkoxy group having 1 to6 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy,isobutoxy, pentyloxy and hexyloxy, for example.

The term a benzene nucleus" when used herein and in the claims, unlessspecifically indicated otherwise, refers to phenyl and substitutedphenyl nuclei such as alkylphenyl, alkoxyphenyl, halophenyl andhydroxyphenyl nuclei, for example. Illustrative alkylphenyl nucleiinclude, for example, (0- ,m-,p- )-methylphenyl, (o-,m-,p-)ethylphenyl,(o-,m-,p-) propylphenyl, (o-,m-,p-)isopropylphenyl and(o-,m-,p-)butyphenyl. (o-,m-,p-)-methoxyphenly, (o-,m-,p-)ethoxyphenyl,(o-,m-,p-)propoxyphenyl, (o-,m-,p-)isopropoxyphenyl and (o-,m-,p-)butoxyphenyl, for example, are illustrative alkoxyphenyl nuclei.(o-,m-,p-)chlorophenyl (o-,m-,p-)fluorophenyl and (o-,m-,p-)bromophenyl,for example, are illustrative halophenyl nuclei. (o-,m-,p-)hydroxyphenylare illustrative of hydroxyphenyl nuclei.

Methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl,butoxycarbonyl, pentyloxycarbonyl and hexyloxycarbonyl, for example, areillustrative of carb(lower alkoxy) groups.

The alkoxycarbonyl isothiocyanate used to form the novel adducts of theinvention has the formula:

wherein wherein e represents an alkyl group such as methyl, ethyl,propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, octyl, decyl, etc.,for example, especially a lower alkyl group.

The novel adducts of the invention are prepared by reacting a tertiaryenamine having the formula 1 with an isothiocyanate having the formula 2without substantial heating to form novel adducts having the formula:

i l i Re C N C 0 Re C n 0 R5 N R.

wherein R R R R and R,have the meaning previously assigned to them.

An adduct having the formula 3 is reacted with ammonia or a primaryamine to form a 4thiouracil having the formula:

wherein R and R,, have the meaning previously assigned to them and R,represents hydrogen or the organic portion of a primary organic amine.

The primary amines which are reacted with the adducts having the formula3 to obtain the 4-thiouracil compounds of the invention have the formulaR,NH wherein R, has the meaning previously assigned to it.

lllustrative of the amines having the formula R NH are, for example,ammonia, alkylamines such as, for example, methylamine, ethylamine,propylamine, isopropylamine, butylamine, isobutylamine, pentylamine,hexylamine, hep- 5 tylamine, octylamine, decylamine, dodecylamine, etc.;hydroxylamine such as, for example, 2-hydroxyethylamine, 3-hydroxypropylamine 3-hydroxybutylamine, 4-hydroxybutylamine,S-hydroxypentylamine, 6-hydroxyhexylamine, etc.; alkoxyalkylamines, suchas, for example, 2-methoxyethylamine, Z-ethoxyethylamine,2-propoxyethylamine, 2- butoxyethylamine, S-methoxypropylamine,3-ethoxypropylamine, 3-propoxypropylamine, 4-methoxybutylamine,4-ethoxybutylamine, etc., aralkylamines such as benzylamine andphenethylamine, for example, a carboxyalkylamine, such as, for example,carboxymethylamine, 2-carboxyethylamine, 3carboxypropylamine,4-carboxybutylamine, 5-carboxypentylamine, 6-carboxyhexylamine, etc.; anH N(CH COO-alkyl amine, wherein n represents a whole number from 1 to 4,such as, for example, H NCH,COOCH H NCH CO OC H H NCH COOC H H NCH COOCH H NCl-l CflgCOOCHa, 1-l NCl-l CHzCOOC H5, H Ngil cl-l COOC H H NCH CHC0OC,H,,, H NCH CH CH COOCH H NCH CH CH COOC H9, H N(CH ).1COOCH HgN 5(CH COOC H5, H N(CH )4COOC H H N(CH COl 00 1-1 etc.; adialkylaminoalkylamine such as, for example, Z-dimethylaminoethylamine,2-diethylaminoethylamine, 2- dipropylaminoethylamine, 2-diisopropylaminoethylamine, 2- dibutylaminoethylamine,3-dimethylaminopropylamine, 3- diethylaminopropylamine,3-dipropylaminopropylamine, 3- diisopropylaminopropylamine,4-dibutylaminopropylamine, 4-dimethylaminobutylamine,4-diethylaminobutylamine, 4- dipropylaminbutylamine,4-diisopropylaminobutylamine, 4 dibutylaminobutylamine; an arylamine,such as, for example, aniline (0-, m-, p-)toluidine, 0-, mp-)ethylaniline (o-, m-, p- )anisidine, (o-, m-, p-)-phenetidine, (o-,m-, p-)chloroaniline, (o-, m-, p-)bromoaniline, (o-, m-,p-)hydroxyaniline, 2,5- dimethoxyaniline, 2,5Diethyoxyaniline,l,2,3,-xylidine, 1,2,4- xylidine, 1,3,2-xylidine, 1,3,4,-xylidine,1,4,2-xylidine, 1,3,5- xylidine, 4-aminodiphenyl, etc., and heterocyclicamines such H r nliraqh m a helifl M.

(H NCH CH N with an alkoxycarbonyl isothiocyanate having the formula 2.

The reaction is carried out without the necessity of heating andpreferably with agitation and at ambient temperature. The reaction canbe carried out in solution in any solvent in which the adducts areinsoluble, such as ether (i.e., diethyl ether), petroleum ether, andmixtures thereof, for example. The preparation of the adducts isillustrated hereinafter. Other solvents that can be used include, forexample, diisopropyl ether, dimethyoxyethane, ligroin, benzene, andchlorinated solvents such as dichloroethane, chloroform,tetrachloroethane and carbon tetrachloride. The use of ether, petroleumether, and mixtures thereof has been found to very satisfactory.Temperatures in the Examples and elsewhere herein are in degreescentigrade unless otherwise indicated.

EXAMPLE 1 1-( N-Carbethoxythiocarbamoyl )-2-morpholino-cyclopentene To awater-cooled, stirred solution of 15.3 g. (0.10 mole) ofl-morpholinocyclopentene in 60 ml. of dry ether was added, dropwise,13.1 g. (0.10 mole) of ethoxycarbonyl isothiocyanate diluted with 15 ml.of dry ether. Soon after addition was begun, a red-orange precipitatebegan to form. After completion of the addition of the isothiocyanate,the mixture was allowed to stir in the cold for 3 hours. The product,l-(N- carbethoxythiocarbamoyl)-2-morpholino-cyclopentene, was isolatedby filtration, washed thoroughly with dry ether, and air-dried. Yield,26.2 g.; m.p. 123-l24. A small sample was recrystallized from methanolas dark red prisms, m.p. l24-12 5.

EXAMPLE 2 2-( N-Carbethoxythiocarbamoyl l -pyrrolidinol -butene To awater-cooled, stirred solution of 12.5 g. (0.10 mole) ofl-pyrrolidino-l-butene in 50 ml. of 1:1 ether-petroleum ether was added,dropwise, 13.1 g. (0.10 mole) of ethoxycarbonyl isothiocyanate in 10 ml.etherpetroleum ether. After addition, stirring was continued for 2.5hours. The orange precipitate, 2-( N-carbethoxythiocarbamoyl)- l-pyrrolidinol butene, was isolated by filtration, washed thoroughly with1:1 ether-petroleum ether, and air-dried. Yield, 19.0 g.; m.p. 72-74. Asmall sample was recrystallized from ether-petroleum ether, then fromether, giving tiny yellow-orange prisms, m.p. 75-77. If after thereaction time given above formation of product is incomplete, a secondcrop can be obtained from the combined washings and mother liquors byplacing them in the cold for several days.

The 4-thiouracil compounds are prepared by reacting an adduct having thefonnula 3 with ammonia or a primary amine. The reaction can be carriedout in solution or suspension. Preferably the reaction is carried outwith agitation, such as stirring. The reaction is normally carried outin the presence of an inert solvent. Suitable solvents include water,alcohols such as ethanol, n-propyl alcohol and isopropyl alcohol, anddimethylformamide, for example. The reaction takes place without thenecessity of heating and is preferably carried out at ambienttemperature. The reaction mixture is preferably cooled just prior tofiltering to insure maximum recovery of the precipitated product. Thiscooling is common practice but is not a part of the reaction per se. Theratio of the reactants can vary widely. As in the case of the formationof the adducts, the reaction proceeds to good yields with conventionaltechniques. The ratio of the reactants is generally equimolar but ratiosof 10 to l and more for either component are operable. The adductcomponent, prepared as described hereinbefore, is suitable for usewithout purification. The preparation of the 4-thiouracil compounds isillustrated by the following Examples.

EXAMPLE 3 6,7-Dihydro- 1 -carbeth0xymethyl-2( 1H )-oxo-5H-cyclopenta-pyrimidine-4( 3H)-thione Glycine ethyl ester was preparedby passing ammonia gas through a chloroform suspension of thehydrochloride, filtering off the salt, concentrating the filtrate anddistilling the oil. The product was stored in a freezer.

Twenty grams (0.070 mole) ofl-(N-carbethoxythiocarbamoyl)-2-(N-morpholine(cyclopentene prepared asin example l was slurried in 70 ml. of ethanol (magnetic stirring) and Iml. of the glycine ethyl ester was added in one portion. After severalminutes, a complete solution was formed, followed shortly by theprecipitation of yellow plates. The mixture was stirred for 30 minutesmore, chilled and filtered. The product was washed with chilled ethanol,a little dry ether, and air-dried. Yield, 16.3 g.; m.p. l79-l80. Tworecrystallizations from ethanol give pale yellow plates; m.p. 183-l 84.

EXAMPLE 4 5-Ethyl-4-thiouracil 8.0 Grams (0.031 mole) ofZ-(N-carbethoxythiocarbamoyl)-l-pyrrolidino-l-butene, prepared as inExample 2, were dissolved in l00 ml. of concentrated aqueous ammonia.The solution was allowed to stand overnight, filtered free of a smalltar residue, then concentrated under reduced pressure to remove the bulkof ammonia. Dropwise acidification with concentrated HCl in the cold topH 3- (Hydrion Paper) gave 4.3 g. of pale yellow product; m.p. 230250Dec. Two recrystallizations from methanol gave analytically purematerial as tiny needles, mp. 250 Dec.

EXAMPLE 5 S-Carbethoxyl 2-hydroxyethyl )-6-methyl-4-thiouracil Ethyl2-(N-carbethoxythiocarbamoyl)-3-dimethylaminocrotonate was prepared fromethoxycarbonyl isothiocyanate and ethyl 3-dimethylaminocrotonate byprocedures similar to those described in Examples 1 and 2 using ether asthe solvent. To a solution of 5 g. (0.017 mole) of this adduct in 40 ml.of dimethylformamide was added 3.5 ml. of 2aminoethanol. The mixture asallowed to stand at room temperature for 16 hours.

The solvent was removed under reduced pressure and the 4 residue takenup in 60 ml. of water. Acidification in the cold gave 3.6 g. of thedesired product as an off-white solid, mp. l-l47. Two recrystallizationsfrom water (one filtration through decolorizing carbon) gaveanalytically pure material as pale yellow prisms, m.p. l47- 1 48.

treated with 3.5 ml. of N-( 2-aminoethyl)morpholine, with stirring. Thestirring effected complete solution of the starting adduct. After 15minutes, the product precipitated. The mixture was allowed to standovernight,'then filtered. Yield 4.3 g., m.p. l67l68. Recrystallizationfrom ethanol gave yellow needles of unchanged melting point.

The mechanism of 4-thiouracil formation is believed to be an amineexchange followed by cyclization. The driving force of the reaction isprobably the cyclization which, under the reaction conditions, isirreversible. This is illustrated as follows:

it has been found that where R,, is phenyl and R and R together completea morpholine radical, the adduct does not ,react with the primary amineto give a thiouracil under the ,reaction conditions mentioned above. itis believed that the bulk or orientation of the phenyl radical may havehindered .the carbon atom to which the phenyl radical is attached to an:extent that the amine was incapable of reaction with same. For lthisreason, it is preferable that R, is hydrogen or an alkyl lgroup havingno more than 3 carbon atoms. When R is an alkyl group, it is preferablymethyl.

The following table shows additional ethoxycarbonylisothiocyanate-tertiary enamine adducts prepared similarly as inexamples 1 and 2.

TABLE i. -ENAMlNE-ET1IOXYUA RBONYL ISOTIUOUYANA'IE ADDUC'IS Recryst.Yield M. l.,

Example No. Enamine solvent percent l-(N-piperidino)-propenu Ether 64115-16 fl-Diethylarnino-styrene Ether ethanol. 80 113-14I-(N-morpholino)-cyclohexen Ether-ligroim. 84 86-871-(N-pyrrolidino)-cyclohexene Ether 87 78-80 Ethylfl-dimethyl-aminocrotonate. Ethanoi 83 148-50 Yields based on crudematerial.

'* Decomposition.

EXAMPLE 6 5 ,6,7,8-Tetrahydro-2( l H )-oxol -phenylquinazoline-4-(3H)-thione l-( N-Carbethoxythiocarbamoyl )-2-morpholinocyclohexene 8.0g. (0.027 mole), was suspended in ml. of ethanol and treated, whilestirring, with 6 ml. of aniline. Complete solution occurred followed byprecipitation of the product.

The mixture was stirred for 30 minutes longer and then filtered. 6.2grams of crude material which darkened above 270 and melted withdecomposition at 280-282 were obtained. Pure product was obtained byrecrystallization from chloroform-ethanol (yellow plates), m.p. 287294Dec.

EXAMPLE 7 l-( 2-Morpholinoethyl)-5-phenyl-4-thiouracil 5 grams (0.016mole) of a( N-carbethoxythiocarbamoyl)-/3- diethylaminostyrene weresuspended in 40 ml. of ethanol and Tables ii, iii and IV show additional4-thiouracil compounds prepared in accordance with the process of theinvention. These compounds were prepared by the general procedure usedin preparing the 4-thiouracil compounds of Examples 3-7.

TABLE III coverage of 459 mg. of silver and 1,040 mg. of gelatin per Ssquare foot. Each emulsion was exposed on an Eastman 18 H sensitometer,processed for minutes in Kodak DK-SO developer, fixed, washed and dried.Four series of emulsions I I 5 were prepared and the results shown inthe table are in relation to a control run for each of the four seriesas is apparent in the table. The preparation of photographic silverhalide emulsions Ex Yield M P such as are suitably stabilized with the4-thiouracils of this in- No it; Recryst. solvent perceni '03 ventiontypically involves three separate operations:

1. emulsification and digestion of silver halide i 23:: m gi jgfijijljlfjj 52 132122 2. the freeing of the emulsion of excesswater-soluble salts, 21.... CiH5 Chl0roformethanol. 89 287-94 22--.. 0110112011 Ethanol 114 234-35 Su'table by washmg. water a l5 3. the seconddigestion or after ripening to obtain in- CHZGHN do 80 21243 creasedemulsion speed or sensitivity.

(Mees, The Theory of the Photographic Process, 1954.) 24" OHzCOOCzHs doU 70 "H2 The new antifoggants can be added to the emulsion be e he Ifinal digestion or after-ripening or it can be added immediate- PP W 2Oly prior to the coating.

NH R J20 i 1 TABLE IV Recryst. Yield, M.P., R; H. Rd solvent percent C.

CH3 Cal-I H Ethanol 90 171-72 CuHs 02115 H d0 83 235-36 CHzOHzOH C2H5 H.do 88 213- OH2CH2N(C2H5)3 CzHs H Ethanol water. 54 124-25 Ha CiH HAceto i1iti'ile 89 282-83 30... CuHs Cal-I5 H Ethanol 88 219- 31 CHzCHzNb 01H. H 83 167438 II CH H Water 210 300 D9FRV PE T-2 2 Theeffectiveness of the 4-thiouracil compounds in reducing The silverhalide emulsion or photographic element confog according to theinvention is shown in Table V hereinafter. taining the antifoggants ofthis invention can contain conven- 4-Thiouracil compounds identified andin the amount tional addenda such as gelatin plasticizers, coating aids,and shown in Table V were added to separate portions of a highhardenerssuch as aldehyde hardeners, e.g., formaldehyde, speed gelatino silverbromoidide emulsion which had been mucocloric acid, glutaraldehydebis(sodium bisulfite), maleic panehromatically sensitized with a cyaninedye. Each emul :dialdehyde, aziridines, dioxane derivatives and sion wascoated on a cellulose acetate su p port at a 0 ypolysaccharides.Spectral sensitizers which can be used are the cyanines, merocyanines,complex (trinuclear) cyanines, complex (trinuclear) merocyanines,styryls, and TABLE hemicyanines, for example. Sensitizing dyes useful insensitiz- Two week ing such emulsions are described, for example, inU.S. Pat. ,335, 31; Fresh mcubam test Nos. 2,526,632 of Brooker andWhite issued on. 24. 1950, Compound oi g./mole Rela- Relaand 2,503,776of Sprague issued Apr. ll, I950. Developing 23%;? g: gg Fog 5313 7 Fogagents can also be incorporated into the silver halide emulsion ifdesired or can be contained in a contiguous layer. Various 100 1. 34 .1446 0. 90 .70 107 38 49 78 silver salts can be used as the sensitive saltsuch as silver brogg 3g 6O mide, silver iodide, silver chloride, ormixed silver halides such 105 5 53 :55 as silver chlorobromide or silverbromoidide. The silver ha- 33 kg: 2E} 1-8; lides used can be those whichform latent images predomi- 3 i: 35 :15 75 1:12 1 nantly on the surfaceof the silver halide grains or those which 3.? g3 g5 form latent imagesinside the silver halide crystals such as 85 1.2g 71 1.13 .21 describedin U.S. Pat. No. 2,592,250 of Davey and Knott is- 107 1.3 87 1.12 .22

91 1.32 74 1.2 .22 S A 1952' 87 1.28 78 1.1 .17 100 1.28 .12 80 1.10 .20The silver halide emulsion layer of a photographic element 2g 1, 33 1%containing the antifoggants of the invention can contain any of 99 1:48:16 04 1. 32 :35 the hydrophilic, water-permeable binding materialssuitable 100 1. 53 .17 n8 1. 40 .29 100 1. 57 97 L30 for this purpose.Suitable materials include gelat n, colloidal 100 1.40 .10 94 1.25 .24albumin, polyvinyl compounds, cellulose derivatives, acryla- 3g 1: 2g :332 1:32 mide polymers, etc. Mixtures of these binding agents can also100 94 7 be used. The binding agents for the emulsion layer of the 1001.33 .16 97 1.12 .36

photographic element can also contain dispersed polymerized vinylcompounds. Such compounds are disclosed, for exam No. 2,614,927 ofBroughton and Woodward issued Oct. 21, ple, in U.S. Pat. Nos. 3,142,568of Nottorf issued July 28, 1952, and asdescribed in the articleStabilization Processing 1964; 3,193,386 of White issued July 6, 1965;3,062,674 of of Films and Papers by H. D. Russell, E. C. Yackel and J.S. Houck, Smi h and Y elSOn is ed N V- 1 2; and Bruce in P.S.A. Journal,Photographic Science and Technique, 3,220,844 of Houck, Smith andYudelson issued Nov. 30, 5 Volume 16B, Oct. 1950.

1965; and include the water-insoluble polymers of alkyl acry- Theantifogging agents of this invention can be incorporated li and m ryryli acid, kyl acryl Or to advantage during manufacture in silver halideemulsions methacrylates and the like. representing the variationsdescribed above. Moreover, fog The silver halide emulsion of aphotographic elemen control in binderless silver halide films preparedby vapor taining the antifoggants of the invention can be coated on a di i f il halid on a itable ort an be wide variety of supports. Typicalsupports are cellulose nitrate hi d b coating h tif in agents f theinvention film, cellulose ester film, polyvinyl acetal film, polystyreneover th vapor d ited l r of ilver halide, polflethylehe tel'ephthalate)mm and related films Combinations of all the above-mentioned addenda canbe resinous materials as well as glass, paper, metal and the like. 1 5 difd i d, pp sueh as P p which are coated with a'elefih The amount ofantifoggant can vary quite widely and, in P y Particularly Polymersefa'olefihs containing two or general, will be less than 1 g. per moleof silver. A greater more carbon atoms, as exemplified y Poll/ethylene,amount can be effectively used where the antifoggant is incor- P YP PYethylehe'butehe eopolymers and the like can porated in a layer otherthan the silver halide emulsion layer, also be p y 20 and a lesseramount, generally less than 0.5 g. per mole of The Speed of thePhotographle emulsions eohtammg the silver, and preferably less than 0.1g. per mole of silver, can be h g of thelhvehtleheah be further eh e byinclud' used in the silver halide emulsion layer. The minimum amount mgm the emulslons a Vanety of hydrophlhc Fonmds Such as is not criticalsince no adverse effect is incurred by using small earboxymethyl Proteinof type descmfed m amounts. However, it is preferred to use at least0.001 g. per 3,001,890 of Gates and Koner Issued e 1961* mole of silverto obtain a suitable level of fog reduction. and polysaccharides of thetype described in Canadian Pat. The 4 thioul.acils useful in preventingfog can be made as 635 f Kouer e Russel! lsued 1962 described herein byreacting a tertiary enamine-alkoxycarbon- Photographic emulsionscontaining the antifoggants of the y] isocyanate adduct with ammonia ora primary amine Cep invention can also contain speed-increasingcompounds such Iain of the thiouracils, however are known and may be asquaternary ammonium compounds, polyethylene glycol or prepared fromtheir uracil analogs by thlation using g l izz ikif gzg221E325:gfi sgizrg j g ggwfi:2; a: phosphorous pentasulfide in pyridine. The overallyield of such reaction is uncertain, however, and it is there ore gg iigg g gzizsgggl Instead or m addmon preferred to utilize 4-thiouraci1sprepared as herein disclosed gg f elements c'omainin the antifo ants ofthe since 4-thiouracils including those condensed with an alicyclic g pg g ring are thus readily obtainable in good yield. The tertiary instantinvention can be used in various kinds of photographic s stems Inaddition to bein useful in X-ra and other nonopenammes andalkoxycarbonyl lsocyanates used m preparing y g y the intermediateadducts according to the invention are tically sensitized systems, theycan also be used in orthochrok Th f d b s k matic, panchromatic andinfrared sensitive systems. The seni es z g gg g ggg tor et sitizingaddenda can be added to photographic systems before 40 a Et f bonylisothlocyanate and its preparation is described by Dixon ft 't d h' h d.Ora er any Sens 2mg yesw 1c are use and Taylor, J. Chem. Soc, Vol. 93,p. 684 (1908). Other al- Silver halide emulsions containing theantifoggants of the invention can be used in color photography, forexample, koxycarbonyl isothlocyanates can be prepared by appropriatevariation of the procedure used by Dixon and Taylor to emulsionscontaining color-forming couplers or emulsions to prepare ethoxycarbonylisothiocyanate.

be developed by solutions containing couplers or other colorgeneratingmaterials, emulsions of the mixed-packet type such Certam 4'thmurac'lannfoggams can also be Prepared y as described in U.S. Pat. No.2,698.794 of Godowsky issued reacting phenoxycarbonyl isothiocyanateswith certain P Jan. 4, 1955; in silver dye-bleach systems; and emulsionsof and Secondary enamines as reported by Goerdelel' et the mixed-graintype such as described in U.S. Pat. No. Chem- 526 (1963) 97 3106 (1964)and 98 (1965) 2,592,243 of Carroll and Hanson issued Apr. 8, 1952. asfollows:

Silver halide emulsions containing the antifoggants of the invention canbe sensitized using any of the well-known S CN 0 5+ a C z techniques inemulsion making, for example, by digesting with naturally active gelatinor various sulfur, selenium, tellun'um S compounds and/or goldcompounds. The emulsions can also H be sensitized with salts of nobelmetals of Group VIII of the R 0C Periodic Table which have an automaticweight greater than 2 N H B R,C=CCSNHCOOC&H5 100. 856

Silver halide emulsions containing the antifoggants of the R3 N F H Cominvention can be used in diffusion transfer processes which R1 utilizethe undeveloped silver halide in nonimage areas of the negative to forma positive by dissolving the undeveloped Silver halide and precipitatingit on a Silver layer in close pro)" it will be noted that R in the4-thiouracil is thus derived from imity to the original silver halideemulsion layer. Such 5 the enamine whereas the analogous radical on theprocesses are described in U.S. Pat. Nos. 2,352,014 of Rott lS- racilsproduced by the present method is derived from primary 9 a124C 5 .4 ofLand i i F 1951; or secondary amine thus giving much wider scope to thissuband 3'O20'l55 of Yackel' Yutzy Foster i Reschfssued stituent on4-thiouracils according to the present method. 1962 The emulsions canalso be used In dlfiuslon transfer The invention has been described indetail with particular color Processes which utilize a diffusiontransfer of an reference to preferred embodiments thereof, but it willbe unimagewise distribution of developer, p y from a derstood thatvariations and modifications can be effected light-Sensitive layer toaseeohd y h while layers are within the spirit and scope. of theinvention as described in close proximity to one another. Silver halide6111111810115 C01)- he einbefore and as defined in the appended claims,taining the antifoggants of the invention can be processed in What isclaimed is:

stabilization processes such as the ones described in U.S. Pat. l. Alight-sensitive silver halide emulsion containing as an antifogganttherein in effective antifoggant amount a 4-thiouracil compound havingthe formula:

S g it Y C=O R N/ wherein R,. represents hydrogen, lower alkyl, loweralkoxy, carb(lower alkoxy) or a benzene nucleus, R represents hydrogenand lower alkoxy and wherein R and R,, collectively represent apolymethylene chain having at least two carbon atoms and R, representshydrogen or the organic portion of a primary organic amine.

2. A light-sensitive silver halide emulsion in accordance with claim 1wherein R, is hydrogen.

3. A light-sensitive silver halide emulsion in accordance with claim 1wherein R, is an alkyl group.

4. A light-sensitive silver halide emulsion in accordance with claim 1wherein R, is a hydroxyalkyl group.

5. A light-sensitive silver halide emulsion in accordance with claim 1wherein R, is a dialkylaminoalkyl group.

6. A light-sensitive silver halide emulsion in accordance with claim 1wherein R, is phenyl or substituted phenyl.

7. A light-sensitive silver halide emulsioh fi ac cordance with claim 1wherein R, is phenyl.

8. A light-sensitive silver halide emulsion in accordance with claim 1wherein 9. A light-sensitive silver halide emulsion in accordance withclaim 1 wherein R and R, collectively represent trimethylene.

10. A light-sensitive silver halide emulsion in accordance with claim 1wherein R and R, collectively represent tetramethylene.

12. A light-sensitive silver halide emulsion in accordance with claim 1containing as an antifoggant 5,6,7,8-tetrahydro- 2( 1H )-oxol-phenylquinazoline-4-( 3H )-thione.

13. A light-sensitive silver halide emulsion in accordance with claim 1containing as an antifoggant 5-ethyl-l-phenyl-4- shio c 14. Alight-sensitive silver halide emulsion in accordance .wit l la llLqwe nsa nti ssa t. x q

15. A light-sensitive silver halide emulsion in accordance with claim 1containing as an antifoggant 5-carbethoxy-l-( 2- h drox eth l)-6-n1 ethyl-4-thi9uracil A 16. A photographic element comprising a supporthaving thereon a layer containing a light-sensitive emulsion of claim 1.

saggy UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,622,3L O Dated November 23, 1971 Inventor(s) Robert W. Lamon It: iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line 10, "2lthiouraoid" should be --l -thiouraoil-; lines 2L4,and 25, "eduction" should be --r-eduction- Column 2, line 58, "e" shouldbe --R Column 3 line 71 "(21-(2-aminoethyl) should be -(2-aminoethyl)-.

Column 5, line 6, "(N-morpholine(oyclopentene" should be--(N-morpholino)oyclopentene; line 37, "Zaminoethanol" should be--2-aminoethanol-- Column 6, line 3L1, "morpholine should bemorpholino--; line 711 "250" should be -280--.

Column 8, line 115, "muoocloric" should be --mucochlorio Column 9, line214., "3,001,890" should be -3,01l,890--; line 58, "automatic" should be-atomic-.

Column 11, line 30, after "wherein" insert "R is -CH CH N 9-- and cancelthe formula extending from lines 31 to 38.

Signed and sealed this 5th day of December 1972.

SEAL) ttest:

\ J DWARD M.FLETCI IEJR ,J'R. RUBERT GOTTSCHALK ttesting OfficerCommissioner of Patents

2. A light-sensitive silver halide emulsion in accordance with claim 1wherein Rf is hydrogen.
 3. A light-sensitive silver halide emulsion inaccordance with claim 1 wherein Rf is an alkyl group.
 4. Alight-sensitive silver halide emulsion in accordance with claim 1wherein Rf is a hydroxyalkyl group.
 5. A light-sensitive silver halideemulsion in accordance with claim 1 wherein Rf is a dialkylaminoalkylgroup.
 6. A light-sensitive silver halide emulsion in accordance withclaim 1 wherein Rf is phenyl or substituted phenyl.
 7. A light-sensitivesilver halide emulsion in accordance with claim 1 wherein Rf is phenyl.8. A light-sensitive silver halide emulsion in accordance with claim 1wherein .
 9. A light-sensitive silver halide emulsion in accordance withclaim 1 wherein Rc and Rd collectively represent trimethylene.
 10. Alight-sensitive silver halide emulsion in accordance with claim 1wherein Rc and Rd collectively represent tetramethylene.
 11. Alight-sensitive silver halide emulsion in accordance with claim 1containing as an antifoggant6,7-dihydro-1-carbethoxymethyl-2(1H)-oxo-5H-cyclopentapyrimidine-4-(3H)-thione.
 12. A light-sensitive silver halide emulsion in accordance withclaim 1 containing as an antifoggant5,6,7,8-tetrahydro-2(1H)-oxo-1-phenylquinazoline-4-(3H)-thione.
 13. Alight-sensitive silver halide emulsion in accordance with claim 1containing as an antifoggant 5-ethyl-1-phenyl-4-thiouracil.
 14. Alight-sensitive silver halide emulsion in accordance with claim 1containing as an antifoggant 5-ethyl-4-thiouracil.
 15. A light-sensitivesilver halide emulsion in accordance with claim 1 containing as anantifoggant 5-carbethoxy-1-(2-hydroxyethyl)-6-methyl-4-thiouracil.
 16. Aphotographic element comprising a support having thereon a layercontaining a light-sensitive emulsion of claim
 1. 17. A photographicelement comprising a support having thereon a layer containing alight-sensitive emulsion of claim
 9. 18. A photographic elementcomprising a support having thereon a layer containing a light-sensitiveemulsion of claim 10.